As I found out, one way to fix it is to have a solid mesh with no geometry or UV cuts. But at this point, I can’t afford to re-do my cave walls/floor/ceiling. That would practically mean starting the whole project from scratch.
If I disable tessellation, then the whole thing is seamless. But naturally, surfaces do not look nearly as good w/o tessellation.
Is there any way to mitigate this problem somehow?
I managed to reduce the seams between the floor and the walls by adjusting my height textures for the floor. Tweaking them this way and that way, and then placing a row of deferred decals on top, all the way around the cave perimeter, to further mask the seam.
By using Pixel Depth Offset on the ceiling, and adjusting my geometry here and there, I achieved seamless transition between the meshes.
The downside to that are two things:
-First, the mesh that is using material with Pixel Depth Offset must have “cast shadows” disabled. Otherwise it breaks the illusion.
-Second, I couldn’t use detailed texture simultaneously with Pixel Depth Offset. Not sure why exactly.
These two reasons are why I had to do some voodoo magic and hope for the best to cover seams between the floor and the walls, instead of jut adding Pixel Depth Offset to it.